Significance of Ochratoxin A in Breakfast Cereals from the United

Feb 9, 2015 - A total of 489 samples of corn-, rice-, wheat-, and oat-based breakfast cereal were collected from U.S. retail marketplaces over a two-y...
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Significance of Ochratoxin A in Breakfast Cereals from the United States Hyun Jung Lee, and Dojin Ryu J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/jf505674v • Publication Date (Web): 09 Feb 2015 Downloaded from http://pubs.acs.org on February 18, 2015

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Journal of Agricultural and Food Chemistry

Significance of Ochratoxin A in Breakfast Cereals from the United States

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Hyun Jung Lee and Dojin Ryu*

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School of Food Science, University of Idaho, 875 Perimeter Drive MS 2312, Moscow, Idaho

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83844–2312, USA

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*Corresponding author. Tel: 208-885-0166; Fax: 208-885-2567; E-mail: [email protected]

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ABSTRACT

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Ochratoxin A (OTA) has been found in all major cereal grains including oats, wheat, and barley

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worldwide and considered as a potential concern in food safety. A total of 489 samples of corn-,

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rice-, wheat-, and oat-based breakfast cereal were collected from the U.S. retail marketplaces

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over a 2-year period and OTA was determined by high-performance liquid chromatography.

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Overall, 201 samples (42%) were contaminated with OTA in the range of 0.10 and 9.30 ng/g.

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The levels OTA were mostly below of the European Commission Regulation (3 ng/g) except in

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16 samples of oat-based cereals. The incidence of OTA was highest in oat-based breakfast

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cereals (70%, 142/203), followed by wheat-based (32%, 38/117), corn-based (15%, 15/103) and

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rice-based breakfast cereals (15%, 10/66). Based on the incidence and concentration of OTA,

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oats and oat-based products may need greater attention in further surveillance program and

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development of intervention strategies to reduce health risk in consumer.

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KEYWORDS: Ochratoxin A (OTA), food safety, breakfast cereal, United States

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INTRODUCTION Ochratoxin A (OTA, Fig. 1) has received attention in recent years as one of the most

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commonly occurring mycotoxins in the world. OTA is considered to be a potent renal

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carcinogen based on experimental animal studies and has been classified as a possible human

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carcinogen, Group 2B.1-3 In addition, OTA has shown to be teratogenic, embryotoxic, genotoxic,

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neurotoxic, and immunosuppressive.1, 4-7 Therefore, OTA has become increasingly regulated by

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many countries, including the European Union (EU), to minimize chronic exposure from this

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potent toxin.8-12 In the EU, the maximum limits for OTA are 5 ng/g in raw cereal grains and 3

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ng/g in processed cereal products.8, 9 The Codex Alimentarius Commission has also established

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guideline for OTA in raw wheat, barley, and rye (5 ng/g).13 OTA has been widely detected in

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cereals and cereal-derived products among many agricultural products.14-16 The toxin is mainly

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produced by the fungi in two distinctively different genera with varying physiological

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characteristics, i.e. Aspergillus ochraceus and Penicillium verrucosum.17 Several studies

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demonstrated that moisture and temperature are two major factors affecting the occurrence of

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OTA.18-20 The incidence and level of mycotoxin contamination are also closely related to the

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geographic location, type of grains, and agronomic practices as well as to the harvesting,

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stocking, and transport conditions.21 Therefore, it is plausible to expect seasonal and regional

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variations when monitoring OTA in agricultural crops. In addition, although there may be some

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difference in the quality, the difference between organic and conventional products in regards to

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mycotoxin contamination has not been clearly demonstrated.22-24

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Grains may be contaminated by mycotoxins during the growing period and/or storage.

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Regardless of the point of fungal infestation, failure to prevent fungal growth and toxin

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production in the field or in storage will inevitably lead to a health risk to the consumer since

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most mycotoxins are relatively heat-stable within the range of conventional food processing

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temperatures (80 – 120ºC). OTA has a melting point of 169°C and is nearly stable when heated

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to 200°C,25, 26 and Boudra et al.27 reported that OTA was not completely destroyed up to 250ºC.

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Consequently, OTA may not be completely removed from the food supply and is difficult to

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destroy under normal industrial food processing or cooking conditions.

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Monitoring the occurrence of OTA in breakfast cereals is important as they are consumed

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on a daily basis. In contrast to the European countries, only a limited number of studies have

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been reported from the U.S. and OTA is not currently regulated in the U.S. Recently we

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reported the occurrence of OTA from a total of 114 breakfast cereals collected in the U.S. during

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one year period.28 In that study, oat-based breakfast cereal showed high incidence (84% or 47/56)

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and high level of contamination ranging 0.14 - 9.10 ng/g, with ten samples exceeding the

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maximum limit (3 ng/g) in the EU. Hence, the objective of this study was to investigate the

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occurrence of OTA in breakfast cereals by expanding the survey of OTA with additional samples

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obtained from the same locations in the U.S. and considering seasonal variations. We also

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attempted to relate the occurrence of OTA with different agricultural practices (organic vs.

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conventional), as these may also affect the occurrence of mycotoxins.

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MATERIALS AND METHODS Chemicals and Materials. OTA standard was purchased from Fluka (St. Louis, MO).

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Stock standard solution with a concentration of 100 mg/L was prepared in methanol and working

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standards were prepared by appropriate dilution in a mixture of methanol/water (50:50, v/v). All

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standard solutions were prepared in amber vials and stored at –20 °C in the dark. HPLC grade

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methanol and acetonitrile were purchased from Fisher Scientific (Pittsburgh, PA), and acetic acid

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(99.5%), sodium acetate (> 99%) and phosphate buffered saline (PBS) tablets were obtained

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from Sigma-Aldrich (St. Louis, MO). OchraTestTM immunoaffinity columns (IAC) were

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purchased from VICAM (Watertown, MA).

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Sampling. To influence the potential variations of OTA levels in different growing

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seasons, the samples were collected over 2 years (2012-13, first year; 2013-14, second year).

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Commercially available breakfast cereal samples were randomly collected from different local

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retail markets across the U.S. Sampling locations included Pittsburg (PA), Chicago (IL), San

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Francisco (CA), Lincoln (NE), Moscow (ID), Fargo (ND) and Minneapolis (MN) for the first

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year. Samples for the second year were obtained from the same locations except East Lansing

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(MI) was included instead of Pittsburg. A total of 489 samples of breakfast cereals with corn (n

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= 103), wheat (n = 117), rice (n = 66) or oat (n = 203) as the major ingredient were obtained.

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Samples were retail products in consumer-size packages or multiple packages of the same lot

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number to total 1 kg. The contents of each package were ground to pass a 2-mm sieve and

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thoroughly mixed and stored in plastic bags at –20°C until analysis. Each sample was mixed

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again before removal of the analytical portion.

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OTA Analysis by HPLC-FLD. Analysis of OTA in breakfast cereal was carried out by

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following the method used previously.28 In brief, a portion of ground sample (25 g) was

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extracted with 100 mL of acetonitrile/water (80:20, v/v) by shaking for 30 min using a wrist

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action shaker (Burrell Scientific, Pittsburgh, PA). The extract was then filtered through

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Whatman No. 4 filter paper and 10 mL of the filtrate was diluted with 40 mL of PBS. A total of

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10 mL of the diluted extract was passed through IAC at a flow rate of about 2 – 3 mL/min. The

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column was washed with 10 mL of PBS followed by 10 mL of water and OTA was eluted with 3

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mL of methanol into a vial at a flow rate of 2 – 3 mL/min. Then the eluate was evaporated to

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dryness under a gentle stream of nitrogen at 50°C. The residue was re-dissolved in 500 µL

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methanol/water (50:50, v/v) and finally, 50 µL of the aliquot was injected into HPLC (Agilent

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1260 Infinity HPLC system, Palo Alto, CA) equipped with a quaternary pump, an autosampler, a

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vacuum degasser, and a fluorescence detector. The chromatographic separation was performed

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on a reverse-phase symmetry Hypersil GOLD C18 column (3 × 100 mm, particle size 1.9 µm,

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Thermo Scientific, Hudson, NH) with isocratic elution using 50% acetonitrile and 50% water

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containing acetic acid 1% at flow rate of 0.4 mL/min. OTA was detected at 334 nm and 460 nm

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wavelengths for excitation and emission, respectively.

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Statistical Analysis. All statistical analyses were performed using the Statistical Package

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for Social Sciences version 12.0 (SPSS Inc., Chicago, IL). The statistical significance of

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differences was determined using unpaired Student’s t tests at a significance level of p < 0.05.

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All data are reported as means ± standard deviations (SD).

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RESULT AND DISCUSSION General. A total of 489 breakfast cereal samples including 126 from 2012-1328 and 363

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from 2013-14 were analyzed. The overall average detection limit was 0.03 ng/g.28 In addition,

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the mean recoveries for spiked samples ranged from 95 to 100%. Results of this study indicated

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that levels of OTA in breakfast cereals collected from the U.S. local markets were generally low,

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except oat-based breakfast cereal samples (Table 1). Overall, 48% (61 out of 126 samples) of

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the samples collected from the first year were contaminated with OTA, while 40% (144 out of

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363 samples) from the second year had OTA in the range of 0.10 – 9.30 ng/g. The mean

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concentration of OTA among positive samples from the first-year (1.51 ng/g) was higher than

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that of the second year samples (0.60 ng/g) but the difference was not statistically significant (p

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< 0.05). It should be noted that the OTA incidence in oat-based cereal (70%, 142/203) was the

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highest followed by wheat (32%, 38/117), corn (15%, 15/103) and rice (15%, 10/66). In this

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study, ten samples from the first year and six samples from the second year exceeded the

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maximum limit established by the European Commission Regulation for OTA in cereal products

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(3 ng/g).

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Previous studies suggested that OTA was the most widespread mycotoxin in cereal grains

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and breakfast cereals surveyed. Araguas et al.29 detected OTA in 59 of the 118 cereal samples

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including wheat, barley and corn from Spain ranged from 0.07 to 7.61 ng/g with the mean

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concentration 0.27 ng/g. More recently, OTA was detected in 19 of the 31 samples of breakfast

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cereals (0.07 – 0.98 ng/g) from the same country.14 Another report from Greece reported similar

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data with 60% incidence rate of OTA among 55 of breakfast cereal samples ranging from 0.02 to

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0.87 ng/g.30 Molinie et al.20 showed that 69% (31 out of 45) of breakfast cereal samples from

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France were contaminated with OTA, with levels of 0.2 to 8.8 ng/g. In 201031 very high levels of

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OTA ranging from 5.1 to 224.6 ng/g were found in breakfast cereals and infant cereals from

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Morocco while the incidence rate was low at 6%. This particular study was alarming as all

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positive samples were above the maximum level set by the European Commission Regulation for

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OTA in cereal-based products.

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Corn – Of the 103 corn samples surveyed, OTA was found in 9% (5 out of 44, mean =

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0.23 ng/g) and 17% (10 out of 59, mean = 0.21 ng/g) samples from the first year and the second

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year, respectively. A Canadian study reported lower maximum concentration (0.15 ng/g) and

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mean concentration (0.12 ng/g) of OTA, although the incidence of OTA in corn-based cereal

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(18%, 6/34) was similar to the current study.32 Puntaric et al.33 observed that 33% (17 out of 51)

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of the corn samples were contaminated with OTA, in concentration range of 0.02 – 40.00 ng/g.

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Rice – Lombaert et al.34 suggested that rice-based breakfast cereals were least likely to be

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contaminated with the mycotoxin as OTA was not detected in any samples from Canada. In this

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study, however, OTA was detected in three samples out of 12 (mean = 0.10 ng/g) from the first

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year and in seven out of 54 rice-based breakfast cereals (mean = 0.25 ng/g) collected in the

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second year (Table 1). This result was similar to the study by Roscoe et al.,32 which reported

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that OTA was detected in 10% (3 out of 29) of the rice-based breakfast cereals analyzed, with a

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mean concentration of 0.13 ng/g. According to Miraglia and Brera,35 18% (4 out of 22) contained

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OTA with a mean concentration of 0.11 ng/g in samples from the European countries.

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Contamination of OTA in rice and rice-based products was also reported from the United

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Kingdom (8% or 3/40, ranged 1 – 19 ng/g)36 and Vietnam (8% or 2 out of 25, at 21.3 and 26.2

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ng/g).37 Gonzalez et al.16 reported that 8% (5 out of 64) of conventional rice and rice-based

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product samples from Spain had OTA concentration ranging from 4.3 to 27.3 ng/g, while organic

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rice and rice-based products showed higher incidence of OTA (30% or 6 out of 20) ranging from

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1.0 to 7.1 ng/g. In a Portuguese study, OTA was detected in 14% (6 out of 42) of the rice

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samples at concentrations ranging from 0.09 to 3.52 ng/g.38 Park et al.39 also observed that 9%

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(13/148) of the rice samples were contaminated with OTA while 9 samples were above the EU

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limit for cereal grains intended for human consumption. According to Zinedine et al.,40 the

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incidences of OTA in rice samples from Morocco was 90%, ranging from 0.01 – 34.5 ng/g, and

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with 15% of the total number of rice samples exceeding the EU maximum limits for cereals.

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More recently, OTA was detected in 26% (26 out of 100) of rice samples, and the concentration

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of OTA in positive samples ranged from 0.08 to 47.00 ng/g. Moreover, 14% (14 out of 100) of

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the rice samples exceeded the maximum level set in the EU.41

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Wheat – Of the 117 samples analyzed, 32% (38/117) were found to contain OTA. The

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incidence and mean concentration of OTA among positive samples in the first year (43%, 0.37

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ng/g) were higher than those in the second year (31%, 0.23 ng/g) as shown in Table 1. A survey

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from Canada reported an incidence of OTA in wheat-based breakfast cereals of 38% (11 out of

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29) with the mean concentration of 0.3 ng/g.37 In wheat samples from the U.S., Trucksess et al.41

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reported a lower incidence of 15% (56/383), while four wheat samples exceeded the maximum

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limit established by the European Commission Regulation (5 ng/g). Puntaric et al.32 observed

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that 76% (74 out of 92) of the corn samples were contaminated with OTA, in the range of 0.02 –

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160 ng/g.

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Oat – OTA was detected in 47 out of 56 oat-based breakfast cereal samples from the first

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year in the range of 0.14 to 9.10 ng/g, with a mean concentration of 1.88 ng/g. In the second year,

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OTA was detected in 65% (95/147) of the samples in the range of 0.12 – 9.30 ng/g with a mean

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concentration of 0.79 ng/g. The differences in the incidence of OTA between the samples

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collected in two separate years indicate seasonal variations. However, the ranges observed in

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this study were almost identical. Notably, 16 samples out of 203 (8%) of oat-based breakfast

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cereals, although it was a small fraction, exceeded the EU maximum limit of 3 ng of OTA/g for

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cereal derived products. According to Roscoe et al.,37 OTA was found most frequently in oat-

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based cereals (63%, 17/27) while the highest maximum concentration (1.40 ng/g) and mean

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concentration of OTA (0.61 ng/g) were lower than those observed in this study. Wolff 43 also

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reported a lower incidence of OTA (39%) in oat flakes. The survey on about occurrence of OTA

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in cereal samples which were collected from Bulgarian villages with a history of Balkan endemic

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nephropathy, found that 78% (7 out of 9) of oat samples were contaminated with OTA, in

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concentration range of 0.89 – 85 ng/g.44 The OTA contamination of oat flake for babies and

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children from Poland, investigated in 1990 – 1992, showed high concentration (35 ng/g), but low

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incidence (1 out of 12).45 Another study conducted in 1999 indicated that OTA was detected in

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100% in the range of 2.0 – 72 ng/g in polished oat samples.45 According to Kuzdralinski et al.,46

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OTA ranging from 1.0 to 5.8 ng/g was detected in 42 among 71 samples of oats from Poland in

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2006 – 2008.

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Conventional vs. Organic. The results obtained from the first year showed that 54%

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(29/54) of organic samples and 44% (32/72) of conventional samples were contaminated with

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OTA. The mean concentration of OTA in conventional samples (1.76 ng/g) was higher than that

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of organic samples (1.23 ng/g). The result of the second year showed opposite trend with 38%

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(60 out of 158) of organic samples and 41% (84 out of 205) of conventional compared with the

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result of the first year. The mean concentration among positive organic samples (0.64 ng/g) was

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higher than that of conventional samples (0.57 ng/g). Nonetheless, the level and incidence of

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OTA were not significantly different between the two groups in both years (p < 0.05).

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Comparison between conventional and organic cereal crops in 1997 and 1998 have been reported

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by Czerwiecki et al.18, 19 In 1997, the frequency of OTA in the organic rye, wheat, and barley

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samples was substantially higher than that from conventional cereal crops. In particular, wheat

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samples from organic farms showed 7.7% of incidence with the highest level of 1.2 ng/g, while

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OTA was not detected in conventional wheat. They also observed a substantial variation of OTA

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contamination levels in three cereal crops between 1997 and 1998. The occurrence, mean

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concentration and the highest level were 49%, 267 ng/g and 1,024 ng/g, respectively, in

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conventional wheat in comparison to 24%, 1.17 ng/g and 1.60 ng/g in organic samples.

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According to Juan et al.,47 the organic cereal grains including rice, wheat, barley, rye, oats, and

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maize samples (72%, mean = 1.64 ng/g) from Spain and Portugal showed higher incidence and

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contamination level of OTA than non-organic samples (28%, mean = 0.05 ng/g). Similar trend

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was observed in rye and rye flour samples with higher mean concentration of OTA in organic

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samples in a multi-year survey.48 A higher level of contamination in organic samples was also

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observed in rice by Gonzalez et al.16

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Sampling Location. Considerable variations in the occurrence of OTA by different

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geographic locations were observed as shown in Table 2. In the first year, the highest incidence

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of contamination was recorded from the samples collected in Dallas (62%), followed by Lincoln

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(58%), Chicago (52%), Moscow (41%), San Francisco (38%), and Fargo/Minneapolis (32%).

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The mean concentration of OTA by sampling location ranged from 0.10 ng/g to 2.94 ng/g with

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no relationship to the incidence. In the second year, the highest incidence of OTA was observed

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in the samples collected in Chicago (58%), followed by San Francisco (53%), Moscow (48%),

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Dallas (42%), East Lansing and Lincoln (32%), and Fargo/Minneapolis (20%).

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Estimated Daily Intake of OTA. Based on the occurrence and the serving size (30 g)

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suggested by the manufacturer, daily intake of OTA was estimated (see Table 3). The

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relationship between the calculated OTA intake and the tolerable daily intake (TDI) proposed by

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the Joint FAO/WHO Expert Committee on Food Additives (JECFA, 14 ng/kg of body

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weight/day)11 and by the EU Scientific Committee for Food (SCF, 5 ng/kg body weight/day),12

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has been expressed as percentages. The values of OTA intake estimated in this study were low

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with less than 7% of TDI proposed by JECFA or 19% of more stringent TDI by SCF even when

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consuming oat-based breakfast cereal. Although these values may be considered insignificant,

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the accumulation of OTA in the body due to its long half-life (~35 days)49 and inter-species

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variation50-52 needs to be considered during exposure assessment. It should be also noted that

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breakfast cereals are only one of the many possible sources of OTA for humans.

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These results suggest that the prevalence and high levels of OTA contamination mainly

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in oat-based products must be acknowledged with caution. To alleviate potential problems with

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OTA, advanced knowledge and practice in Good Agricultural Practice (GAP) and other on-farm

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management system must be emphasized to reduce initial fungal infestation and subsequent OTA

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accumulation. Best practice in grain storage and further downstream processes should also be

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carefully reviewed and employed to warrant safe food supply since OTA may not be destroyed

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or eliminated by conventional food processing technologies. In addition, more research is

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needed to optimize food processing conditions to effectively reduce OTA to ensure food safety

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and understand the changes occurring in the cereals during processing. This study also suggests

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a need for greater effort in monitoring OTA in food supply for additional data and potential

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concern in public health from the long term exposure of this potent mycotoxin.

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ACKNOWLEDGEMENT

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This project was supported by Agriculture and Food Research Initiative Competitive

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Grant No. 2011-67005-20676 from the USDA National Institute of Food and Agriculture.

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Sampling was conducted in collaboration with Charlene Wolf-Hall (North Dakota State

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University), Jayne Stratton and Dr. Andreia Bianchini (University of Nebraska-Lincoln), Jeffery

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Palumbo (USDA/WRRL), Jack Cappozzo (Illinois Institute of Technology), Lauren Jackson

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(FDA/CFSAN), and Felicia Wu (University of Pittsburg, later moved to Michigan State

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University).

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IARC, International agency for research on cancer. In Geneva, 1993; Vol. 56, pp. 489.

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Table 1. Occurrence of ochratoxin A (OTA) in breakfast cereals collected from the United States. 2012-13 (first year)*

2013-14 (second year)

Type

Main Ingredient

Incidence (%)

Mean ± SD (ng/g)

Range (ng/g)

Incidence (%)

Mean ± SD (ng/g)

Range (ng/g)

Conventional

Corn

3/23 (13%)

0.23 ± 0.09

0.12 – 0.28

6/34 (18%)

0.27 ± 0.13

0.15 – 0.52

Rice

3/12 (25%)

0.10 ± 0.01

0.10 – 0.11

4/32 (13%)

0.26 ± 0.14

0.11 – 0.44

Wheat

4/11 (36%)

0.11 ± 0.01

0.10 – 0.12

17/61 (28%)

0.27 ± 0.33

0.10 – 1.49

Oat

22/26 (85%)

2.49 ± 2.20

0.22 – 9.10

57/78 (73%)

0.71 ± 1.14

0.12 – 6.87

Total

32/72 (44%)

1.76 ± 2.12

0.10 – 9.10

84/205 (41%)

0.57 ± 0.37

0.10 – 6.87

Corn

2/21 (10%)

0.24 ± 0.03

0.22 – 0.26

4/25 (16%)

0.12 ± 0.01

0.11 – 0.13

Rice

-

-

-

3/22 (18%)

0.23 ± 0.20

0.11 – 0.46

Wheat

2/3 (67%)

0.87 ± 0.89

0.24 – 1.50

15/42 (36%)

0.20 ± 0.08

0.10 – 0.35

Oat

25/30 (83%)

1.34 ± 1.82

0.14 – 7.43

38/69 (55%)

0.90 ± 1.88

0.12 – 9.30

Total

29/54 (54%)

1.23 ± 1.72

0.14 – 7.43

60/158 (38%)

0.64 ± 1.53

0.10 - 9.30

61/126 (48%)

1.51 ± 1.94

0.10 – 9.10

144/363 (40%)

0.60 ± 1.23

0.10 – 9.30

Organic

Overall

SD: standard deviation of three replicates; ND: not detected; -: no sample * Adopted from Nguyen and Ryu (2014).29

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Table 2. Occurrence of ochratoxin A in breakfast cereals from different locations in the U.S. in 2012-13 (first year) and 2013-14 (second year). Incidence (%)

Mean ± SD (ng/g)

Range (ng/g)

Sampling Location

Main Ingredient

First year*

Second year

First year*

Second year

First year*

Second year

Chicago

Corn Rice Wheat Oat Corn Rice Wheat Oat Corn Rice Wheat Oat Corn Rice Wheat Oat Corn Rice Wheat Oat Corn Rice Wheat Oat Corn Rice Wheat Oat

1/10 (10%) 10/11 (91%) 1/7 (14%) 0/2 (0%) 15/17 (88%) 0/11 (0%) 7/11 (64%) 3/9 (33%) 4/8 (50%) 0/8 (0%) 6/8 (75%) 3/8 (38%) 0/1 (0%) 2/6 (33%) 9/9 (100%)

1/5 (20%) 1/8 (13%) 3/8 (38%) 18/19 (95%) 1/8 (13%) 9/16 (56%) 1/8 (13%) 1/10 (10%) 3/22 (14%) 18/33 (55%) 0/10 (0%) 0/8 (0%) 3/16 (19%) 7/16 (44%) 3/8 (38%) 2/8 (25%) 7/16 (44%) 11/16 (69%) 3/12 (25%) 3/12 (25%) 11/22 (50%) 23/29 (79%) 1/8 (13%) 0/8 (0%) 5/19 (26%) 11/18 (61%)

0.12 ± 0.00 2.01 ± 1.69 0.26 ± 0.00 1.08 ± 1.47 ND 2.84 ± 2.10 0.10 ± 0.01 0.11 ± 0.01 ND 2.94 ± 3.18 0.28 ± 0.03 ND 0.87 ± 0.09 1.64 ± 2.25

0.28 ± 0.00 0.18 ± 0.00 0.15 ± 0.03 0.83 ± 1.20 0.13 ± 0.00 1.09 ± 2.19 0.52 ± 0.00 0.29 ± 0.00 0.35 ± 0.14 0.64 ± 1.14 ND ND 0.59 ± 0.78 0.61 ± 0.80 0.20 ± 0.08 0.12 ± 0.01 0.19 ± 0.07 0.32 ± 0.28 0.13 ± 0.02 0.34 ± 0.20 0.18 ± 0.08 0.78 ± 1.31 0.17 ± 0.00 ND 0.18 ± 0.09 1.31 ± 2.71

0.12 0.22 – 5.20 0.26 0.14 – 5.67 ND 0.20 – 6.75 0.10 – 0.11 0.10 – 0.12 ND 0.34 – 7.10 0.22 – 0.28 ND 0.24 – 1.50 0.22 – 7.43

0.28 0.18 0.13 – 0.18 0.14 – 3.71 0.13 0.12 – 6.87 0.52 0.29 0.21 – 0.48 0.12 – 4.97 ND ND 0.12 – 1.49 0.13 – 2.39 0.11 – 0.26 0.11 – 0.13 0.11 – 0.30 0.12 – 0.98 0.11 – 0.15 0.11 – 0.46 0.10 – 0.34 0.13 – 5.54 0.17 ND 0.10 – 0.29 0.12 – 9.30

61/126 (48%)

144/363 (40%)

1.51 ± 1.94

0.60 ± 1.23

0.10 – 7.43

0.10 – 9.30

Dallas

East Lansing

Fargo/ Minneapolis

Moscow

San Francisco

Lincoln

Total

SD: standard deviation of three replicates; ND: not detected; -: no sample * Adopted from Nguyen and Ryu (2014).29

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Table 3. Estimated daily intake of ochratoxin A (OTA, ng/kg of body weight/day) and the percentage that it represents of the proposed tolerable daily intake (TDI) by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food of European Union (SCF).

Sample Year First year

Seocnd year

Main Ingredient

OTA Intakea (ng/g)

OTA Exposureb (ng/kg of bw/day)

JECFAc (%)

SCFd (%)

Corn

0.23

0.12

1

2

Rice

0.10

0.05

0

1

Wheat

0.37

0.19

1

4

Oat

1.88

0.94

7

19

Average

1.51

0.76

5

15

Corn

0.21

0.11

1

2

Rice

0.25

0.13

1

3

Wheat

0.23

0.12

1

2

Oat

0.79

0.4

3

8

Average

0.60

0.30

2

6

a

Based on the recommended intake on the label of the package, 30 g per serving.

b

Estimated exposure based on the body weight (bw) of 60 kg.

c

Based on the TDI of OTA for humans at 14 ng/kg bw/day established by JECFA.

d

Based on the TDI of OTA for humans below 5 ng/kg of bw/day established by SCF.

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OH O

C H C

CH2

O

OH

O

C N

O

H

H CH3

Cl

Fig. 1

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Journal of Agricultural and Food Chemistry

O

OH C

O

OH

O

100 CH C H2

First-year Second-year Total

C N H

O H

80

CH3 Cl

Incidence (%)

Ochratoxin A (OTA)

60

40

20

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t

e

TOC

W he a

ic R

at O

Co rn

0